Now, I’m no Superman fan… therefore I was really baffled to discover that the fictional Kryptonite has a chemical structure! However, the “real life Kryptonite” doesn’t look as cute as the comic version though. Quoting the linked BBC article:

According to movie and comic-book storylines, kryptonite is supposed to sap Superman’s powers whenever he is exposed to its large green crystals.

The real mineral is white and harmless, says Dr Chris Stanley, a mineralogist at London’s Natural History Museum.

“I’m afraid it’s not green and it doesn’t glow either – although it will react to ultraviolet light by fluorescing a pinkish-orange,” he told BBC News.

Well, I guess the pinkish-orange reaction to UV would be good enough. And yeah, the mineral’s scientific name is Jadarite. Probably to avoid potential trademark disputes with DC comics 😛